JP4011809B2 - Torque hinge structure and portable office equipment - Google Patents

Description

【００２１】
以上は、軸部材１０の径大部１１の軸方向の面粗度Ｒａとトルク保持率とに関する研究、考察であるが、さらに、本願発明者は軸部材１０の径大部１１の真円度及び周方向の面粗度Ｒａに注目して、トルク保持率を長期間に亙って維持するための研究、考察を行った結果、以下に示すような事実が明らかになった。
【００２２】
真円度とトルク保持率との関連を考察するに当たって、本願発明者は、軸部材１０の径大部１１の外周における真円Ｓ（例えば、目標軸径を有する真円）に対する内側最大変位位置、すなわち、真円Ｓに対する最大深さ（へこみ）Ｖと、基準中心円としての真円Ｓに対する遠心側最大変位位置値、すなわち、真円Ｓに対する最大高さＰに注目した。研究、考察を行った結果、トルク保持率が長期間に亙って維持されるためには、最大深さＶを、Ｖ＜１μｍ、最大高さＰと最大深さＶとの差として表される真円度「Ｐ−Ｐ」を、Ｐ−Ｐ＜２．５μｍとすることで、長期間に亙って安定したトルク保持率が確保されることを見い出した。
【００２３】
図８では、上記の研究結果を導き出すために用いた真円度の計測方法の模試図を（ａ）に、外周における真円に対する最大高さＰ及び最大深さＶとの関係を（ｂ）にそれぞれ示す。なお、測定にあたっては、ＪＩＳＢ７４５１に規定された測定方法によって計測し、ＪＩＳＢ０６２１に規定された真円度の定義に従った表現方法で表示した。
表２に、本発明を導き出すために用いた試料における各測定値を示す。
表２において、ヒンジ型Ｎｏは成形用金型の番号を示し、試料Ｎｏは各金型における試料番号を示すもので、３種類の金型について、計９種類の試料を成形したことを示している。
【表２】

【００２４】
図９に上記測定による各測定値とトルク保持率との関係を示す。
図９（ａ）では、最大高さＰと最大深さＶとの差として表される真円度「Ｐ−Ｐ」とトルク保持率との関係を示す。
図９（ａ）で明らかなように、用いた金型に関係なく、真円度「Ｐ−Ｐ」とトルク保持率との間には、真円度「Ｐ−Ｐ」の値が小さい場合には、トルク保持率の値が小さく、真円度「Ｐ−Ｐ」の値が大きいほど、トルク保持率が大きくなることが分かる。この結果から、最大高さＰから最大深さＶまでの差が小さく真円度が優れたものほど、トルク保持率が小さくできることが分かる。
【００２５】
図９（ｂ）では、最大高さＰとトルク保持率との関係を示す。
図９（ｂ）で示されるとおり、最大高さＰの値とトルク保持率とには、相関は見られず、最大高さＰを抑えるだけでは、トルク保持率を向上させることができないことが分かる。これは、軸部材１０における最大高さＰは、各加工工程においてチッピングとして生じたものであり、周方向の極く限られた部分のみに存在するもので、面摩擦抵抗に対して継続的に影響を及ぼすことがないためであると考えられる。
【００２６】
図９（ｃ）では、最大深さＶとトルク保持率との関係を示す。
図９（ｃ）で示されるとおり、最大深さＶの値とトルク保持率とには、上記の（ａ）に示した真円度「Ｐ−Ｐ」とトルク保持率との相関よりも、更に明確な相関が見られ、外周における最大深さＶとしてのくぼみの大きさが、トルク保持率に対して最も大きな影響を与えることが分かる。
特に、最大深さＶが１μｍ以下である場合には、トルク保持率は著しく小さくなり、最大深さＶを１μｍ以下にすることで優れた耐久性が確保されることが分かる。
これは、軸部材１０の外周面におけるくぼみは、軸方向及び周方向にある程度の長さを有して存在するため、欠落容積が大きいからであると考えられる。
【００２７】
表３に、上記真円度「Ｐ−Ｐ」、最大深さＶを、軸部材１０の径大部１１の軸方向及び周方向の面粗度Ｒａと合わせて、トルク保持率への影響を調べた結果を示す。
【００２８】
【表３】

表３から明らかなとおり、周方向の面粗度Ｒａが０．１７μｍ以下のものであっても、最大深さＶが１μｍ以上であると、トルク保持率が急激に低下することが分かる（試料Ｎｏ１，２，４，５，９，１０，１３）。
また、試料Ｎｏ７のものは、最大深さＶが１μｍ以下であるが、周方向の面粗度Ｒａが０．０５μｍ以下の小さい値であるため、軸回動支持部材２０の樹脂と凝着しやすく、軸部材１０の回動時に異音が発生するため適さない。
【００２９】
次に、以上の真円度及び面粗度Ｒａを確保するための、軸部材１０の表面加工方法について説明する。
各種の加工法の違いによる軸部材１０の仕上がり仕様を、軸方向と周方向の各面粗度Ｒａについて、図１０及び図１１に示す。
ここでは、図１０（ａ）にフィルム研磨、図１０（ｂ）にバレル研磨、図１０（ｃ）に化学研磨、図１１（ａ）に化学研磨、図１１（ｂ）に転写転造、図１１（ｃ）に転造のみをそれぞれ示す。
図１０、図１１に示すとおり、表面加工を施すことで、いずれの加工方法を用いた場合でも、軸方向の面粗度Ｒａに対して周方向の面粗度Ｒａを０．１〜０．２μｍ程度小さくすることができる。
【００３０】
特に、図１０（ａ）に示したフィルム加工と、図１１（ｂ）に示した転写転造では、周方向の面粗度Ｒａを軸方向の面粗度Ｒａに対して明らかな差を生じさせることができる。このため、周方向の面粗度Ｒａが０．０５μｍを上回り、かつ０．２０μｍ以下に小さく仕上げることで、良好なトルク保持率となり、長期間に亙って安定したトルク保持率を確保することができる。これと同時に、軸方向の面粗度Ｒａを周方向の面粗度Ｒａよりも０．１〜０．２μｍ程度大きくすることによって、軸部材１０と軸回動支持部材２０との間に安定したトルクを確実に発生させることができる。
【００３１】
次に、上記の表面加工を含め、軸部材１０の成形加工について簡単に説明する。
加工方法としては、塑性加工と切削加工とがある。
［１］塑性加工
塑性加工を行う場合には、冷間鍛造、温間鍛造、熱間鍛造、鋳造法などの加工時に、真円度「Ｐ−Ｐ」が、Ｐ−Ｐ＜６〜７μｍとなるように引き抜き加工工程を行い、その後、２段以上の円筒研削及びセンタレス研磨を施す。
切削、研磨では、１段目に加工時のＰ−Ｐの２〜３倍を研磨する荒研削を施し、２、３段目には、真円度「Ｐ−Ｐ」、最大深さＶを、Ｐ−Ｐ＜２．５μｍ、Ｖ＜１μｍに仕上げるための上記各仕上げ研磨工程を施す。
【００３２】
［２］切削加工
切削加工を行う場合には、切削加工により真円度「Ｐ−Ｐ」をＰ−Ｐ＜３〜４μｍを確保し、その後、センタレス研磨、円筒研削、フィルム研削などの表面加工によって真円度「Ｐ−Ｐ」を２．５μｍに仕上げる。
【００３３】
上記のように表面加工を施された軸部材１０を回転摺動させる軸回動支持部材２０に用いられる樹脂材料としては、軸部材１０に対して安定した摩擦力を確保するために、トルクヒンジ構造体１を使用温度範囲（例えば、−２０〜８０℃）における曲げ弾性率（ＧＰａ）の変化の割合が小さい樹脂を用いている。
これは、種々の樹脂について、トルク保持率と曲げ弾性率保持率との関係を調べたところ、図１２に示すとおり、トルク保持率が８０％以上となる樹脂材料では、曲げ弾性率保持率が８０％以上であることに基づくもので、曲げ弾性率保持率が高い（使用温度範囲内における曲げ弾性率の変化の割合が小さい）樹脂材料を用いることで、高いトルク保持率を実現できるからである。
【００３４】
図１３、図１４に、周囲の環境温度と樹脂製部材の曲げ弾性率との関係を示す。
図１３に示すＰＡＲ（ポリアリレート）では、実際に機器等が使用される周辺の環境温度範囲内では、曲げ弾性率が大きく変化しないため、軸回動支持部材２０として適しているが、図１４に示すような一般の結晶性樹脂では、使用温度範囲内で温度によって曲げ弾性率が大きく変化する。このため、こうした一般の結晶性樹脂では、使用温度が変化した場合に軸部材１０に対して適切な摩擦力を与えることができず、軸回動支持部材２０には適していないことが分かる。
【００３５】
以上の観点から、軸回動支持部材２０として用いるのに適した樹脂材料の具体例としては、ＰＡＲ（ポリアリレート）、ＰＣ（ポリカーボネイト）、ＰＰＳ（ポリフェニレンサルファイド）、ＰＥＳ（ポリエーテルサルホン）、ＰＥＥＫ（ポリエーテルエーテルケトン）などが挙げられる。
【００３６】
次に第２実施例について説明する。
第２実施例では、軸回動支持部材２０に用いられる樹脂材料として、上述のＰＡＲ（ポリアリレート）、ＰＣ（ポリカーボネイト）、ＰＰＳ（ポリフェニレンサルファイド）、ＰＥＳ（ポリエーテルサルホン）、ＰＥＥＫ（ポリエーテルエーテルケトン）などの単一材料ではなく、これらにフッ素系樹脂、オレフィン系樹脂等の有機系の摺動剤を１０ｗｔ％以内で添加して用いる。また、カーボン、カーボン繊維、二硫化モリブデン、チタン酸カリウムなどの無機系摺動剤を１０ｗｔ％以内で添加してもよい。
樹脂材料にＰＴＦＥを３ｗｔ％添加した場合を図１５に、添加しない場合を図１６にそれぞれ示す。添加した場合には、初動時に滑らかに回動を開始することが分かる。
また、これによって、軸部材１０と軸回動支持部材２０との摩擦に伴って発生する摩擦粉を著しく低減させることができる。
図１７に、これらの摺動剤を添加した場合の耐久性について、添加しないものと比較して示す。
図から明らかなとおり、摺動剤を添加した場合には、トルク保持率の低下の度合いが著しく小さくなっており、長寿命のヒンジとすることができる。
【００３７】
次に、第３実施例について説明する。
第３実施例では、軸回動支持部材２０の強度を向上させるために、ミネラル、カーボン繊維、ガラス繊維などを４０ｗｔ％以内で添加する。
【００３８】
以上のとおり、本発明では、軸部材１０の軸方向の面粗度Ｒａを、０．１５〜０．３０μｍに仕上げているため、スティックスリップの発生や初動時のひっかかりがなく、軸部材１０と軸回動支持部材２０との間に安定した摩擦力を維持させることができる。
また、軸部材１０の周方向の面粗度Ｒａを軸方向の面粗度Ｒａよりも０．１〜０．２μｍ程度小さくして、０．０５μｍを上回り、かつ０．２０μｍ以下であるように仕上げるとともに、真円度「Ｐ−Ｐ」及び最大深さＶをそれぞれ２．５μｍ、１μｍ以下に設定して、表面加工を行っているため、良好なトルク保持率となり、長期間に亙って安定したトルクを確保することができる。
従って、蓋部材等（図示せず）の開閉において、蓋部材等を任意の開閉角度で容易に保持させることができる。
また、軸回動支持部材２０を軸部材１０とモールド一体成形によって組付けているため、製造コストの低減を図ることができる。
また、軸回動支持部材２０として成形される樹脂製部材に、使用温度範囲における曲げ弾性変化率が小さい材料を用いている。このため、種々の使用環境においても、軸部材１０と軸回動支持部材２０との間に安定した摩擦力を維持することができるようになり、蓋部材等を備えた機器の使い勝手をよくすることができる。
【００３９】
上記実施例では、面粗度Ｒａを設定するために、表面加工を施した例を示したが、軸部材の加工時に表面加工ができる工程（一例、転造加工）を設け、軸部材の軸方向の面粗度Ｒａ、及び周方向の面粗度Ｒａを０．１５〜０．３０μｍ及び０．５〜０．２０μｍに直接仕上げてもよい。
上記実施例では、軸部材の表面処理を行わないものを示したが、防錆及び耐久性向上のための表面処理として、膜厚５〜１５μｍのＮｉ−Ｐメッキ、或いは硬質Ｃｒメッキなどを施した後に、各研磨による表面加工を施してもよい。
上記実施例では、ノート型パソコンなどの蓋部材を例に挙げたが、開閉される蓋状の部材であれば、複写機の蓋、便器の蓋等他のものでもよい。
【図面の簡単な説明】
【図１】本発明のトルクヒンジ構造体を示す斜視図である。
【図２】実施例のトルクヒンジ構造体の軸部材を示す図で、（ａ）は正面図、（ｂ）は側面図である。
【図３】実施例のトルクヒンジ構造体を示す図で、（ａ）は側面図、（ｂ）は正面図である。
【図４】本発明の性能を説明するため軸部材の軸方向の面粗度と所定回数使用後におけるトルク保持率との関係を示す特性図である。
【図５】本実施例の軸部材の軸方向の面粗度が最適と考える場合の回動角度とトルクとの特性図である。
【図６】図５と比較するための軸部材の軸方向の面粗度が大きい場合の回動角度とトルクとの特性図である。
【図７】図５と比較するための軸部材の軸方向の面粗度が小さい場合の回動角度とトルクとの特性図である。
【図８】本発明における軸部材の真円度を測定方法を説明するための図で、（ａ）は測定方法を示す概略図、（ｂ）は最大高さＰ、真円度「Ｐ−Ｐ」と最大深さＶを示す軸部材の断面図である。
【図９】図８により測定した真円度の各測定値とトルク保持率との相関を示す相関図である。
【図１０】各表面加工方法による軸部材の軸方向と周方向の各面粗度の測定結果を示す図で、（ａ）はフィルム研磨、（ｂ）はバレル研磨、（ｃ）は化学研磨の場合をそれぞれ示す。
【図１１】各表面加工方法による軸部材の軸方向と周方向の各面粗度の測定結果を示す図で、（ａ）は化学研磨、（ｂ）は転写転造、（ｃ）は転造のみの場合をそれぞれ示す。
【図１２】各種の樹脂材料における曲げ弾性率保持率とトルク保持率との関係を示す特性図である。
【図１３】本実施例に用いた曲げ弾性率の変化が小さい樹脂材料における温度と曲げ弾性率との関係を示す特性図である。
【図１４】図１３と比較するための一般の結晶性樹脂における温度と曲げ弾性率との関係を示す特性図である。
【図１５】第２実施例を説明するための図で、軸回動支持部材の樹脂材料に摺動剤を添加した場合の回動角度とトルクとの関係を示す特性図である。
【図１６】図１５と比較するための図で、軸回動支持部材の樹脂材料に摺動剤を添加しない場合の回動角度とトルクとの関係を示す特性図である。
【図１７】第２実施例の軸回動支持部材の樹脂材料に摺動剤を添加した場合の耐久回数とトルクの変化との関係を、摺動剤を添加しない場合と合わせて示した図である。
【符号の説明】
１ トルクヒンジ構造体
１０ 軸部材
２０ 軸回動支持部材[0001]
BACKGROUND OF THE INVENTION
The present invention includes, for example, an opening / closing lid of a portable office device such as a laptop notebook computer and a hinge used for swinging and supporting a display, and various other types including an intermediate stop at an arbitrary opening / closing angle. The present invention relates to a torque hinge structure suitable for opening and closing a lid member.
[0002]
[Prior art]
Conventionally, as a friction structure for suppressing rotational torque in a torque hinge for rotating and stopping and fixing a lid member or the like to an arbitrary angle, a resin mold is integrally formed so as to include a metal rotating shaft. There is something that supports it freely.
In such a configuration, the rotation axis can be rotated and fixed at an arbitrary angle by making the metal rotation shaft and the resin relatively rotatable while having a surface frictional resistance.
[0003]
[Problems to be solved by the invention]
However, in a torque hinge having such a structure, if the relationship between the contact state of the interface between the rotating shaft and the resin containing the rotating shaft is not appropriate, the rotational torque varies greatly, and stick slip occurs during rotation. There is a problem that abnormal noise is generated, or the durability is low and the torque cannot be maintained due to wear.
In order to solve these problems, research on surface processing such as the surface roughness of the rotating shaft has been conducted conventionally, but all of these are only considerations regarding the surface roughness in the axial direction of the metal rotating shaft. However, little research has been conducted on the circumferential direction of the rotating shaft.
This is because, in the production of a rotating body such as a rotating shaft, cutting and polishing are routinely carried out by rotating processing, and therefore, considerations regarding the roundness of the rotating shaft and the surface roughness in the circumferential direction are mostly made. It seems that it was not.
The inventor of the present application, as a result of repeated research on the relationship between the metal rotating shaft and the resin containing it, can maintain the torque over a long period of time, and in order to improve the durability of the torque hinge, It has been found that there is an appropriate relationship between the roundness of the rotating shaft and the values of both the circumferential direction of the rotating shaft and the surface roughness in the axial direction, which have not been considered so far.
[0004]
An object of the present invention is to provide a torque hinge structure that maintains a stable frictional force that can be easily fixed at an arbitrary angle for a long period of time when a lid member or the like is opened and closed.
[0005]
[Means for Solving the Problems]
The present invention according to claim 1 includes a metal shaft member having a rotation shaft serving as a rotation center, and a shaft rotation support member that supports the shaft member with the rotation shaft so that the rotation angle is relatively rotatable. The shaft rotation support member is provided so as to be relatively rotatable around the rotation shaft of the shaft member, and includes a resin member that encloses the rotation shaft and is molded integrally with the outside of the rotation shaft. The shaft rotation support member is configured to generate a surface friction resistance between the shaft member and the shaft rotation support member using a surface pressure generated by a tightening margin based on molding shrinkage of the resin member. In the torque hinge structure, the measurement is performed by the measurement method defined in JISB7451 and displayed by the expression method according to the definition of roundness defined in JISB0621. Maximum centrifugal side The value PP determined by the difference between the position and the inner maximum displacement position is PP <2.5 μm, and the torque holding ratio between the shaft rotation support member and the shaft member is 80% or more of the initial torque. Yes, The surface roughness in the circumferential direction on the outer peripheral surface of the rotating shaft is measured by the measuring method shown in JIS B0601, and is set as the surface roughness Ra shown by the expression method according to the definition defined in JIS B0601, and the surface roughness Ra is 0. Set to be above 0.05 μm and below 0.20 μm, The surface roughness Ra in the axial direction on the outer peripheral surface of the rotating shaft is set in a range of 0.15 to 0.30 μm.
[0007]
Contract Claim 2 For portable office equipment, claims 1 Using the torque hinge structure described above, the display unit is rotatably supported by the torque hinge structure.
[0008]
[Operation and effect of the invention]
In the present invention, the shaft rotation support member including the rotation shaft is configured by being integrally formed on the outside of the rotation shaft by a resin member. The integral molding process is performed by integral molding in which a previously disposed shaft member is placed in a high temperature mold and a resin member is pushed into the mold. Therefore, after the integral molding, when the temperature of the shaft member and the resin member is lowered, the resin member contracts, and stress due to tightening is generated to closely contact the shaft member.
The shaft rotation support member that is in close contact with the shaft member due to the allowance for molding shrinkage generates a frictional force on the contact surface against the rotational force of the shaft member. As a result, when the shaft member receives a rotational torque from the outside with a large force with respect to the frictional force with the shaft rotation support member, the shaft member rotates relative to the shaft rotation support member and friction The shaft member does not rotate with respect to a rotational torque smaller than the force, and the shaft member is maintained at an arbitrary rotation angle by the frictional force.
As a result, the shaft member and the shaft rotation support member can be assembled by integral molding of the mold, and can be manufactured at a low cost as an integrally molded body.
The torque retention rate between the shaft rotation support member and the shaft member being 80% or more means that the bending elastic modulus retention rate of the resin member in the shaft rotation support member is 80% or more, and high torque. This is because the retention rate can be realized.
Further, the surface roughness Ra in the axial direction of the rotating shaft is set to 0.15 to 0.30 μm, which is larger than the surface roughness Ra in the circumferential direction to give a difference therebetween. Thereby, it is possible to easily set a necessary frictional force between the rotation shaft (shaft member) and the shaft rotation support member, and it is possible to prevent the generation of abnormal noise due to stick-slip during rotation, Friction based on rotation can be suppressed, and the shaft member can be stopped and maintained at an arbitrary rotation angle over a long period of time.
In addition, since the surface roughness Ra in the circumferential direction of the rotating shaft exceeds 0.05 μm and is 0.20 μm or less, the smoothness of the peripheral surface of the rotating shaft is ensured and the resin member Adhesion can be prevented, and appropriate lubricity can be secured on the contact surface between the peripheral surface of the rotating shaft and the resin member, and the generation of noise or the like can be eliminated when the shaft member rotates. Note that reducing the surface roughness in the circumferential direction of the rotating shaft relative to the surface roughness in the axial direction can be realized by performing various surface treatments on the outer circumferential surface of the shaft member.
[0009]
The outer peripheral surface of the rotating shaft is finished into a cylindrical shape by drawing or cutting. However, according to the research and consideration of the inventors of the present application, the depth value V of the inner maximum displacement position with respect to the perfect circle, That is, the depression with respect to the perfect circle is 1 μm or more, or the roundness “PP” determined by the difference between the centrifugal maximum displacement position and the inner maximum displacement position with respect to the reference center circle on the outer periphery of the rotating shaft is 2.5 μm or more. It was found that the torque retention rate was drastically decreased and the durability was impaired.
In the first aspect, the outer periphery of the rotating shaft is required to be molded such that V <1 μm and PP <2.5 μm and the roundness is high. By finishing so that it can be maintained, a torque hinge structure having excellent durability can be provided.
[0011]
Claim 2 In portable office equipment, since there is little wear between the rotating shaft (shaft member) and the shaft rotation support member and it is possible to hold it with a stable torque, a display mounted on a lid member or the like can be used for a long time. Therefore, it can be held at an arbitrary rotation angle.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
The torque hinge structure 1 of the present invention will be described below with reference to the drawings.
A torque hinge structure 1 shown in FIG. 1 is used for opening and closing a lid on which a liquid crystal display is mounted in a notebook personal computer or the like as a portable office device. In order to adjust the display angle of the liquid crystal display, This is for fixing the lid at an arbitrary opening / closing angle.
The torque hinge structure 1 is attached to a lid member of a personal computer, and a shaft member 10 that rotates together with the lid member, and the shaft member 10 is rotatably supported on the main body side of the personal computer to open and close the lid member. It consists of a shaft rotation support member 20. In this case, since the rotational displacement of the shaft member 10 with respect to the shaft rotation support member 20 is relative, the shaft rotation support member 20 may be configured to be rotatably supported with respect to the shaft member 10. Is possible.
[0013]
As shown in FIG. 2, the shaft member 10 has a large diameter portion 11 (for example, a diameter of 5 mm) as a middle portion of a cylindrical rod material made of a metal such as SUS material (stainless steel) or steel, and both ends thereof are large The small diameter portions 12 and 13 (for example, 4 mm in diameter) having a smaller diameter than the portion 11 are formed, and further, a tenon portion 14 for fitting with the lid member is formed at the tip of one small diameter portion 13. .
[0014]
As shown in FIG. 3, the shaft rotation support member 20 is a resin member formed in close contact so as to cover the outside of the large diameter portion 11 of the shaft member 10. It is formed by molding integrally with the shaft member 10 by injection molding of a resin material. Here, the mold temperature is set to around 165 ° C., and the mold is integrally formed.
[0015]
Since the torque hinge structure 1 needs to set the lid member at an arbitrary angle with respect to the personal computer body as described above, the relative torque applied to the shaft rotation support member 20 and the shaft member 10 is predetermined. When the torque is equal to or lower than the torque, the relative angle is maintained. When the torque is equal to or higher than the predetermined torque, it is necessary to ensure smooth rotation.
Specifically, a stable friction torque of about 1 to 20 kgf · cm is required, and the durability is required to be about 50,000 times. When this durability is used, the torque retention is 80% or more of the initial torque. It is a condition.
The torque retention rate is defined by the following equation.
Torque retention ratio (%) = (Torque after degradation and torque / initial torque) × 100
[0016]
FIG. 4 shows the results of tests conducted by changing the surface roughness Ra in order to find the surface roughness (surface roughness) Ra in the axial direction of the large diameter portion 11 of the shaft member 10 for satisfying the above conditions. .
As shown in FIG. 4, when the desired durability is used, the torque retention rate is 80% or more, but when the surface roughness Ra is 0.02 to 0.08 μm, it is too fine to satisfy, but 0.15 to It is satisfactory at 0.30 μm. In addition, when the surface roughness Ra is fine, the torque variation itself increases, and stick slip occurs during operation (during rotation), and abnormal noise such as squeak noise is also clarified.
In this case, the surface roughness Ra was measured by the measurement method shown in JIS B0601, and was shown by a display method according to the definition prescribed in JIS B0601.
[0017]
Further, when the surface roughness Ra becomes 0.35 μm or more as shown in FIG. 4, the initial rotation is large, the stick slip is large, and the shaft rotation which is a resin member with a durability of about 1000 times. The wear of the support member 20 increases, and the generated stress due to the interference generated by the contraction cannot be maintained, and the torque retention rate is significantly reduced.
From the above test results, it is clear that the surface roughness Ra in the axial direction of the large-diameter portion 11 of the shaft member 10 supported by the shaft rotation support member 20 is suitably 0.15 to 0.30 μm. It became.
[0018]
Rotation angle and torque when the PAR (polyarylate) resin is used as the shaft rotation support member 20 and the large diameter portion 11 of the shaft member 10 is 5 mm in diameter and the small diameter portion 12 is 4 mm in diameter. FIG. 5 shows the case of the present embodiment in which the surface roughness Ra in the axial direction of the surface of the large diameter portion 11 is 0.18 μm. For comparison, FIG. 6 shows the surface roughness Ra larger than that of the present invention. FIG. 7 shows the case where the surface roughness Ra is finished to 0.02 μm and 0.04 μm, which are smaller than those of the present invention.
[0019]
When the surface roughness Ra in the axial direction is 0.75 μm as in the comparative example, as shown by X in FIG. 6, the initial movement is large, and as shown by Y, the stick slip is large. When the surface roughness Ra is 0.18 μm as in the present invention, it can be seen that these are so small that they are hardly recognized as shown in FIG.
On the other hand, when the surface roughness Ra is set to 0.02 and 0.04 μm as in the comparative example, it can be seen that the stick slip at the time of rotation increases as shown by Z in FIG.
[0020]
Table 1 summarizes the torque required for rotation, stick-slip, and the value of the catch at the time of initial movement with respect to the surface roughness Ra in the axial direction.
[Table 1]

[0021]
The above is research and consideration regarding the axial surface roughness Ra and the torque retention ratio of the large-diameter portion 11 of the shaft member 10. Further, the inventor of the present application further describes the roundness of the large-diameter portion 11 of the shaft member 10. As a result of studies and considerations for maintaining the torque retention ratio over a long period of time focusing on the surface roughness Ra in the circumferential direction, the following facts have been clarified.
[0022]
In considering the relationship between the roundness and the torque retention rate, the inventor of the present application has determined that the inner maximum displacement position with respect to the perfect circle S (for example, a perfect circle having a target shaft diameter) on the outer periphery of the large diameter portion 11 of the shaft member 10. That is, the maximum depth (dent) V with respect to the perfect circle S and the centrifugal maximum displacement position value with respect to the true circle S as the reference center circle, that is, the maximum height P with respect to the true circle S were noted. As a result of research and consideration, in order to maintain the torque retention rate over a long period of time, the maximum depth V is expressed as the difference between V <1 μm and the maximum height P and the maximum depth V. It has been found that by setting the roundness “P−P” to P−P <2.5 μm, a stable torque retention rate can be secured over a long period of time.
[0023]
In FIG. 8, (a) is a schematic diagram of the roundness measurement method used for deriving the above research results, and (b) shows the relationship between the maximum height P and the maximum depth V with respect to a perfect circle on the outer periphery. Respectively. In the measurement, the measurement was performed by the measurement method defined in JISB7451 and displayed by an expression method in accordance with the definition of roundness defined in JISB0621.
Table 2 shows each measured value in the sample used to derive the present invention.
In Table 2, the hinge type No indicates the mold number, and the sample No indicates the sample number in each mold, indicating that a total of 9 types of samples were molded for 3 types of molds. Yes.
[Table 2]

[0024]
FIG. 9 shows the relationship between each measured value obtained by the above measurement and the torque retention rate.
FIG. 9A shows the relationship between the roundness “PP” expressed as the difference between the maximum height P and the maximum depth V and the torque retention rate.
As apparent from FIG. 9 (a), when the value of the roundness “PP” is small between the roundness “PP” and the torque retention rate, regardless of the mold used. It can be seen that the torque retention rate increases as the value of the torque retention rate decreases and the value of the roundness “PP” increases. From this result, it can be seen that the torque holding ratio can be reduced as the difference from the maximum height P to the maximum depth V is small and the roundness is excellent.
[0025]
FIG. 9B shows the relationship between the maximum height P and the torque retention rate.
As shown in FIG. 9B, there is no correlation between the value of the maximum height P and the torque retention rate, and it is impossible to improve the torque retention rate simply by suppressing the maximum height P. I understand. This is because the maximum height P in the shaft member 10 is generated as chipping in each processing step, and is present only in a very limited portion in the circumferential direction. This is thought to be because there is no effect.
[0026]
FIG. 9C shows the relationship between the maximum depth V and the torque retention rate.
As shown in FIG. 9 (c), the value of the maximum depth V and the torque retention rate are larger than the correlation between the roundness “PP” and the torque retention rate shown in (a) above. Further, a clear correlation is seen, and it can be seen that the size of the recess as the maximum depth V on the outer periphery has the greatest influence on the torque retention rate.
In particular, when the maximum depth V is 1 μm or less, the torque retention rate is remarkably reduced, and it can be seen that excellent durability is ensured by setting the maximum depth V to 1 μm or less.
This is presumably because the indentation on the outer peripheral surface of the shaft member 10 has a certain length in the axial direction and the circumferential direction, and therefore has a large missing volume.
[0027]
In Table 3, the roundness “PP” and the maximum depth V are combined with the surface roughness Ra in the axial direction and the circumferential direction of the large-diameter portion 11 of the shaft member 10 to influence the torque retention rate. The results of the investigation are shown.
[0028]
[Table 3]

As is apparent from Table 3, even when the surface roughness Ra in the circumferential direction is 0.17 μm or less, it can be seen that when the maximum depth V is 1 μm or more, the torque retention rate decreases rapidly (sample) No 1, 2, 4, 5, 9, 10, 13).
In the sample No. 7, the maximum depth V is 1 μm or less, but since the circumferential surface roughness Ra is a small value of 0.05 μm or less, it adheres to the resin of the shaft rotation support member 20. This is not suitable because abnormal noise is generated when the shaft member 10 is rotated.
[0029]
Next, the surface processing method of the shaft member 10 for ensuring the above roundness and surface roughness Ra will be described.
The finished specifications of the shaft member 10 due to differences in various processing methods are shown in FIGS. 10 and 11 for the surface roughness Ra in the axial direction and the circumferential direction.
Here, film polishing in FIG. 10 (a), barrel polishing in FIG. 10 (b), chemical polishing in FIG. 10 (c), chemical polishing in FIG. 11 (a), transfer rolling in FIG. Only rolling is shown in 11 (c).
As shown in FIGS. 10 and 11, by applying surface processing, the surface roughness Ra in the circumferential direction is 0.1 to 0. 0 with respect to the surface roughness Ra in the axial direction, regardless of which processing method is used. It can be reduced by about 2 μm.
[0030]
In particular, in the film processing shown in FIG. 10A and the transfer rolling shown in FIG. 11B, there is a clear difference between the surface roughness Ra in the circumferential direction and the surface roughness Ra in the axial direction. Can be The For this reason , Circumferential surface roughness Ra But 0.05 over μm and 0.20μm Less than By finishing it small, Good Torque retention rate Next 亙 for a long time What Stable torque retention can be secured . This and At the same time, the surface roughness Ra in the axial direction is greater than the surface roughness Ra in the circumferential direction. Also By enlarging about 0.1-0.2 μm, Between the shaft member 10 and the shaft rotation support member 20 A stable torque can be generated reliably.
[0031]
Next, the forming process of the shaft member 10 including the surface process will be briefly described.
As processing methods, there are plastic processing and cutting processing.
[1] Plastic working
When performing plastic working, it is drawn so that the roundness “PP” is P−P <6 to 7 μm during cold forging, warm forging, hot forging, casting, etc. The process is performed, and then two or more stages of cylindrical grinding and centerless polishing are performed.
In cutting and polishing, rough grinding is performed to polish 2 to 3 times PP at the first stage, and roundness “PP” and maximum depth V are set to the second and third stages. , P−P <2.5 μm and V <1 μm are applied to the above finish polishing steps.
[0032]
[2] Cutting
In the case of cutting, the roundness “PP” is ensured by cutting so that PP <3 to 4 μm, and then the roundness is obtained by surface processing such as centerless polishing, cylindrical grinding, and film grinding. “PP” is finished to 2.5 μm.
[0033]
As a resin material used for the shaft rotation support member 20 that rotates and slides the shaft member 10 that has been surface-treated as described above, a torque hinge is used in order to ensure a stable frictional force against the shaft member 10. The structure 1 is made of a resin having a small rate of change in flexural modulus (GPa) in the operating temperature range (for example, −20 to 80 ° C.).
As a result of examining the relationship between the torque retention rate and the flexural modulus retention rate for various resins, as shown in FIG. 12, the resin material having a torque retention rate of 80% or more has a flexural modulus retention rate. Because it is based on the fact that it is 80% or more, a high torque retention rate can be realized by using a resin material having a high flexural modulus retention rate (a small rate of change in flexural modulus within the operating temperature range). is there.
[0034]
13 and 14 show the relationship between the ambient environmental temperature and the flexural modulus of the resin member.
The PAR (polyarylate) shown in FIG. 13 is suitable as the shaft rotation support member 20 because the bending elastic modulus does not change greatly within the ambient temperature range around which the device or the like is actually used. In the general crystalline resin as shown in FIG. 1, the flexural modulus changes greatly depending on the temperature within the operating temperature range. For this reason, it can be seen that such a general crystalline resin cannot give an appropriate frictional force to the shaft member 10 when the use temperature changes, and is not suitable for the shaft rotation support member 20.
[0035]
From the above viewpoint, specific examples of resin materials suitable for use as the shaft rotation support member 20 include PAR (polyarylate), PC (polycarbonate), PPS (polyphenylene sulfide), PES (polyethersulfone), Examples include PEEK (polyetheretherketone).
[0036]
Next, a second embodiment will be described.
In the second embodiment, as the resin material used for the shaft rotation support member 20, the above-mentioned PAR (polyarylate), PC (polycarbonate), PPS (polyphenylene sulfide), PES (polyethersulfone), PEEK (polyether). Instead of a single material such as ether ketone), an organic sliding agent such as a fluorine-based resin or an olefin-based resin is added within 10 wt%. Moreover, you may add inorganic type sliding agents, such as carbon, carbon fiber, molybdenum disulfide, and potassium titanate, within 10 wt%.
FIG. 15 shows the case where 3 wt% of PTFE is added to the resin material, and FIG. 16 shows the case where PTFE is not added. When added, it turns out that rotation starts smoothly at the time of initial movement.
In addition, the friction powder generated due to the friction between the shaft member 10 and the shaft rotation support member 20 can be significantly reduced.
FIG. 17 shows the durability when these sliding agents are added in comparison with those not added.
As is apparent from the figure, when a sliding agent is added, the degree of decrease in the torque retention rate is remarkably reduced, and a long-life hinge can be obtained.
[0037]
Next, a third embodiment will be described.
In 3rd Example, in order to improve the intensity | strength of the shaft rotation support member 20, a mineral, carbon fiber, glass fiber, etc. are added within 40 wt%.
[0038]
As described above, in the present invention, since the surface roughness Ra in the axial direction of the shaft member 10 is finished to 0.15 to 0.30 μm, there is no occurrence of stick-slip or catching at the initial movement, Between the shaft member 10 and the shaft rotation support member 20 Maintains stable friction force Let Can.
Further, the surface roughness Ra in the circumferential direction of the shaft member 10 is greater than the surface roughness Ra in the axial direction. Also About 0.1 to 0.2 μm , 0.05 over μm and 0.20μm As below Finish And Since the roundness “PP” and the maximum depth V are set to 2.5 μm and 1 μm or less, respectively, and surface processing is performed, Good Torque retention rate Next For a long time Cheap A fixed torque can be secured.
Therefore, the lid member etc. (Not shown) When opening and closing the lid Etc. At the opening and closing angle Easy to hold be able to.
Moreover, since the shaft rotation support member 20 is assembled with the shaft member 10 by integral molding, the manufacturing cost can be reduced.
Also, the resin molded as the shaft rotation support member 20 For manufacturing parts Using a material with a small bending elastic change rate in the operating temperature range . this Therefore, even in various usage environments, Between the shaft member 10 and the shaft rotation support member 20 A stable friction force can be maintained. Like In addition, it is possible to improve the usability of the device including the lid member.
[0039]
In the above embodiment, an example in which surface processing is performed in order to set the surface roughness Ra is shown. However, a process (for example, rolling processing) that can perform surface processing at the time of processing the shaft member is provided, and the shaft of the shaft member The surface roughness Ra in the direction and the surface roughness Ra in the circumferential direction may be directly finished to 0.15 to 0.30 μm and 0.5 to 0.20 μm.
In the above embodiment, the shaft member is not subjected to the surface treatment. However, as a surface treatment for preventing rust and improving durability, Ni-P plating having a film thickness of 5 to 15 μm or hard Cr plating is applied. Then, surface processing by each polishing may be performed.
In the above embodiment, a lid member such as a notebook personal computer is taken as an example. However, as long as it is a lid-like member that can be opened and closed, other members such as a lid of a copying machine and a lid of a toilet bowl may be used.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a torque hinge structure according to the present invention.
2A and 2B are diagrams showing a shaft member of a torque hinge structure according to an embodiment, wherein FIG. 2A is a front view and FIG. 2B is a side view.
3A and 3B are diagrams showing a torque hinge structure according to an embodiment, wherein FIG. 3A is a side view and FIG. 3B is a front view.
FIG. 4 is a characteristic diagram showing the relationship between the axial surface roughness of the shaft member and the torque retention after a predetermined number of uses in order to explain the performance of the present invention.
FIG. 5 is a characteristic diagram of the rotation angle and torque when the axial surface roughness of the shaft member of the present embodiment is considered optimum.
6 is a characteristic diagram of a rotation angle and torque when the axial surface roughness of the shaft member is large for comparison with FIG. 5. FIG.
7 is a characteristic diagram of the rotation angle and torque when the axial surface roughness of the shaft member is small for comparison with FIG. 5. FIG.
8A and 8B are diagrams for explaining a method for measuring the roundness of a shaft member in the present invention, in which FIG. 8A is a schematic diagram illustrating the measurement method, and FIG. It is sectional drawing of the shaft member which shows P "and the maximum depth V. FIG.
FIG. 9 is a correlation diagram showing a correlation between each measured value of roundness measured in FIG. 8 and a torque retention rate.
FIGS. 10A and 10B are diagrams showing measurement results of the surface roughness in the axial direction and the circumferential direction of the shaft member by each surface processing method. FIG. 10A shows film polishing, FIG. 10B shows barrel polishing, and FIG. 10C shows chemical polishing. Each case is shown.
FIGS. 11A and 11B are diagrams showing the measurement results of the surface roughness in the axial direction and the circumferential direction of the shaft member by each surface processing method. FIG. 11A shows chemical polishing, FIG. 11B shows transfer rolling, and FIG. Each case shows only the structure.
FIG. 12 is a characteristic diagram showing the relationship between the flexural modulus retention rate and the torque retention rate of various resin materials.
FIG. 13 is a characteristic diagram showing a relationship between temperature and bending elastic modulus in a resin material having a small change in bending elastic modulus used in this example.
FIG. 14 is a characteristic diagram showing the relationship between temperature and flexural modulus in a general crystalline resin for comparison with FIG.
FIG. 15 is a diagram for explaining the second embodiment, and is a characteristic diagram showing a relationship between a rotation angle and a torque when a sliding agent is added to the resin material of the shaft rotation support member.
FIG. 16 is a characteristic diagram showing the relationship between the rotation angle and the torque when no sliding agent is added to the resin material of the shaft rotation support member for comparison with FIG. 15;
FIG. 17 is a diagram showing the relationship between the number of durability times and the change in torque when a sliding agent is added to the resin material of the shaft rotation support member of the second embodiment, together with the case where no sliding agent is added. It is.
[Explanation of symbols]
1 Torque hinge structure
10 Shaft member
20 axis rotation support member

Claims (2)

A metal shaft member having a rotation shaft serving as a rotation center;
The shaft member includes a shaft rotation support member that supports the shaft member so as to be relatively rotatable at the rotation shaft.
The shaft rotation support member is provided so as to be relatively rotatable around the rotation axis of the shaft member, includes the rotation shaft, and is formed by a resin member molded integrally with the outer side of the rotation shaft. A rotation support member is configured, and a surface friction resistance is generated between the shaft member and the shaft rotation support member by utilizing a surface pressure generated by a tightening margin based on molding shrinkage of the resin member. In the torque hinge structure,
The maximum displacement position on the centrifugal side relative to the reference center circle on the outer circumference of the rotating shaft and the maximum inner side are measured by the measurement method defined in JISB7451 and displayed in an expression method according to the definition of roundness defined in JISB0621. The value PP determined by the difference from the displacement position is P−P <2.5 μm, and the torque holding ratio between the shaft rotation support member and the shaft member is 80% or more of the initial torque,
The surface roughness in the circumferential direction on the outer peripheral surface of the rotating shaft is measured by the measuring method shown in JIS B0601, and is set as the surface roughness Ra shown by the expression method according to the definition defined in JIS B0601, and the surface roughness Ra is 0. Set to be above 0.05 μm and below 0.20 μm,
A torque hinge structure characterized in that an axial surface roughness Ra on an outer peripheral surface of the rotating shaft is set in a range of 0.15 to 0.30 μm. A portable office device , wherein the torque hinge structure according to claim 1 is used to rotatably support a display unit on the torque hinge structure .

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